This invention relates to processes for preparing dioximinocycloalkanones (i.e. bis [hydroximino]cycloalkanones). The production of these oximino or isonitroso cycloalkanones has been proposed heretofore by reaction of a cycloalkanone, such as cyclohexanone, with nitrosyl chloride, alkyl nitrites, nitric oxide and hydrochloric acid or similar nitrosating agents. A discussion of this technique appears, for example, in U.S. Pat. No. 2,999,875 and U.S. Pat. No. 3,112,345.
Additionally, the preparation of the monooximo substituted ketone, 1-morpholinocyclohexen-(1)-on-(6)-oxime, by reaction of 1-morpholinocyclohexene and nitrosyl chloride in the presence of triethylamine and an inert solvent has been disclosed heretofore by Metzger, Tetrahedron Letters No. 4, pages 203-206 (1964).
The foregoing U.S. Pat. No. 3,112,345, discloses conversion of the dioximinocycloalkanones to the corresponding diamino alcohols by catalytic reduction. These latter compounds are disclosed as having value for use in forming soaps when combined with fatty acids and as absorbents for carbon dioxide from flue gas in the manufacture of dry ice. The former patent, U.S. Pat. No. 2,999,875, discloses the cleavage of the dioximinocycloalkanones to form compounds that are readily converted by reduction to alpha, omega-diamino acids, for example, the alpha, omega-diamino acid, lysine, when the starting material is cyclohexanone, or ornithine if the starting material is cyclopentanone. Ornithine may, in turn, be converted to arginine, by known methods, to produce lysine. Arginine and lysine are important nutritional supplements. Other reaction sequences for converting the foregoing and other dioximinocycloalkanones to useful products are also disclosed in U.S. Pat. No. 2,999,875.
The alkyl nitrites suggested heretofore for nitrosation of cycloalkanones are, it is noted, expensive and productive of reduced yields of the desired dioximino products with significant loss of nitrogen oxide. In addition, the alkyl nitrites are dangerous to handle in that they tend to cause a marked fall in blood pressure; and in larger concentrations tend to produce methemoglobinemia resulting in cyanosis and asphyxia. Many side products are also formed using this nitrosating agent, thus hampering the recovery of the desired dioximinoketones.
If .alpha.,.alpha.'-dioximinoketones, such as disclosed in the foregoing U.S. patents, could be derived from enamines derived from secondary amines and ketones, particularly cycloaliphatic ketones, and if this conversion could, in addition, be accomplished in nearly quantitative yields, including recycling of the products formed with the desired dioximino ketones to produce additional reactant enamine, a novel, unexpected, inexpensive and practical means would be achieved for preparation of compounds of known and valuable utility that would constitute a significant advance in the state of the art.